Cartilage tissue can be found throughout the human anatomy. The cells within cartilage tissue are called chondrocytes. These cells generate proteins (e.g., collagen, proteoglycan, and elastin) that are involved in the formation and maintenance of the cartilage. Hyaline cartilage is present on certain bone surfaces, where it is commonly referred to as articular cartilage. Such cartilage contains significant amounts of collagen (e.g., two-thirds of the dry weight), and cross-linking of the collagen imparts a high material strength and firmness to the tissue. These mechanical properties are important to the proper performance of the articular cartilage within the body.
Osteochondral allografting (“OATS”) is a desirable treatment option to repair large articular defects, providing functional restoration of the affected joint. Traditionally, osteochondral allografts are implanted fresh, within 7 days, and have high chondrocyte viability at implantation. Microfracture surgery is an articular cartilage repair surgical technique that works by creating tiny holes, or fractures, in the bone underlying the cartilage. Blood and bone marrow flow into the damaged area to form a “super-clot”, from which new cartilage develops. However, this technique has several limitations, including lack of efficacy for large and deep osteochondral defects, limited availability, non-filled spaces between the circular grafts, and incomplete integration of the donor and recipient cartilage.